WO1996017044A1

WO1996017044A1 - Thickened bleaching compositions, method of use and process for making them

Info

Publication number: WO1996017044A1
Application number: PCT/US1995/015495
Authority: WO
Inventors: Giulia Ottavia Bianchetti; Sergio Cardola; Luigi Pace; Kevin Graham Blyth; Elizabeth Ann Shaw
Original assignee: The Procter & Gamble Company
Priority date: 1994-11-25
Filing date: 1995-11-14
Publication date: 1996-06-06
Also published as: MX9703841A; DE69529533D1; EP0793707B1; AR000201A1; CA2204507C; DE69529533T2; ATE231910T1; CA2204507A1; EP0793707A1; JPH10509992A; AU4370896A; ES2189834T3; BR9509822A

Abstract

The invention relates to stable thickened acidic aqueous compositions comprising a source of active oxygen or mixtures thereof as well as a quaternary ammonium compound together with a short chain amine oxide, i.e. an amine oxide having the following formula R1R2R3NO, wherein R2 and R3 are independently C1-C4 alkyl groups and wherein R1 is a C6 to C10 alkyl group. Said compositions are particularly suitable for the cleaning of non-horizontal surfaces.

Description

THICKENED BLEACHING COMPOSITIONS, METHOD OF USE AND PROCESS FOR MAKING THEM

Technical field

The present invention relates to aqueous bleaching compositions, more particularly to stable acidic thickened aqueous compositions comprising a source of active oxygen. Said compositions find particular application in the cleaning of hard-surfaces, especially inclined hard-surfaces, such as toilet bowls and the like.

Background

A great variety of bleaching and cleaning compositions have been described in the art. Bleaching/cleaning compositions comprising a source of active oxygen and formulated at low pH are particularly interesting for the cleaning of hard-surfaces, especially for the hygienic cleaning of sanitary fittings such as toilet bowls and the like. Representative of this technical field is, for instance, EP-A-598 694 which discloses acidic aqueous compositions comprising persulfate salts which are preferably in the form of an emulsion of nonionic surfactants.

However, such compositions have not been found satisfactory as regards their residence time on the surface to be cleaned in particular if the surface is wet. Indeed, it is desired to formulate compositions having greater residence time on non-horizontal surfaces such as inclined wall of a toilet bowl when applied thereto, allowing thereby that said compositions perform their cleaning action for longer periods of time. There are many such compositions known in the art that have the requisite viscosity characteristics. However, most of the thickeners known in the art, whilst allowing to effectively increase the viscosity of aqueous acidic compositions, do have some disadvantages in use. Indeed, thickeners like nonionic surfactants (nonyl phenol ethoxylates) or quaternary ammonium compounds have the disadvantage that they require to be used at high levels to achieve satisfactory viscosity, thus making them expensive to use. Also, some thickeners show significant instability in acidic medium, especially in acidic medium with hydrogen peroxide, or a source thereof, like monopersulfate. Indeed, some thickeners are easily oxidizable by sources of active oxygen, like monopersulfate, in aqueous acidic compositions, leading thereby to a loss of the total amount of active oxygen which would otherwise be available to perform bleaching action on the surface to be cleaned. In other words, some thickeners do not allow to formulate acidic aqueous compositions comprising a source of active oxygen with satisfactory chemical stability for long storage periods.

It is thus an object of the present invention to formulate acidic aqueous compositions comprising a source of active oxygen having improved thickening properties.

It is a further object of the present invention to formulate acidic aqueous compositions comprising a source of active oxygen with high thickening at low total thickening surfactant level. It is another object of the present invention to formulate thickened aqueous acidic compositions comprising a source of active oxygen which are chemically stable for long storage periods.

It has now been found that the above mentioned objects could be met by formulating an acidic aqueous composition comprising a source of active oxygen and, as the thickening system, a quaternary ammonium compound together with a short chain amine oxide (C6-C10). More particularly, it has unexpectedly been found that the addition of a small amount of a short chain amine oxide to a quaternary ammonium compound, as the thickening system, in an acidic aqueous composition comprising a source of active oxygen allows to formulate highly thickened aqueous acidic compositions as compared to the use of only said quaternary ammonium compound, as the thickening system, i.e. a thickening system being free of any short chain amine oxide. Alternatively, the present invention allows to use low level of total thickening surfactant to achieve a given viscosity for an acidic aqueous composition comprising a source of active oxygen. In other words, to obtain a desired thickening effect for a given acidic aqueous composition, a lower level of total thickening surfactants (quaternary ammonium compounds and short chain amine oxides) is sufficient in the present invention, as compared to the level of quaternary ammonium compound which would otherwise be required to obtain the same thickening effect when used alone, in absence of any short chain amine oxide. This thickening effect is even more noticeable in the preferred compositions of the present invention wherein said source of active oxygen is a persulfate salt such as monopersulfate salt. Indeed, it has been found that said persulfate salt together with said quaternary ammonium compound act as a thickening system.

It has further been found that the thickening system of the present invention exhibits good stability in acidic medium and in presence of strong oxidants like sources of active oxygen. Indeed, the decomposition of said source of active oxygen, e.g. persulfate salt, is reduced with the thickening system of the present invention as compared to other surfactant blends like for instance alkylethoxylated alcohols. In other words, sources of active oxygen in thickened aqueous acidic compositions of the present invention are chemically stable for longer periods of storage. An advantage of the present invention is that the stable thickened aqueous acidic compositions comprising a source of active oxygen according to the present invention are less sensitive to the presence of perfumes. Indeed, the thickening system of the present invention allows to formulate stable acidic aqueous compositions comprising a source of active oxygen and still having high viscosity, despite the presence of perfumes, even at high levels. In fact, high levels of perfume are known to have a general tendency to significantly decrease composition viscosity by changing micellar aggregation.

Another advantage of the present invention is that said stable thickened aqueous acidic compositions are efficient on various surfaces to clean various soils and stains. Additionally, said compositions when used to treat hard surfaces, especially toilet bowls, exhibit outstanding soil discoloration, soil solubilization and emulsification properties together with a germicidal action, this when used both neat or diluted.

A further advantage is that the present invention allows to formulate compositions which are clear, as opposite to clouded, and thus well accepted from a consumer view point. Also the present invention allows to formulate compositions that are Newtonian. By "Newtonian" it is meant herein a composition which has the same viscosity within a very wide range of applied shear stresses.

In the field of thickened aqueous acidic compositions the following patent applications are representative of the prior art.

EP-A-275 043 discloses an acidic cleaner for aluminium surfaces containing a peroxide, acids, a C12-C22 alkyl dimethylamine oxide. Said cleaner has a pH at most 2. EP-A-275 043 discloses cationic surfactants as optional ingredients but no specific compounds of this class of surfactants are mentioned, let alone quaternary ammonium compounds.

EP-A-265 979 discloses acidic thickened aqueous cleaning composition comprising a disinfecting and/or oxidizing agent, an organic anionic sulphonate and a surfactant selected from the group of (1 ) quaternary ammonium compounds wherein at least one of the hydrocarbon groups linked to the nitrogen is a linear or branched alkyl group containing at least 12 carbon atoms and of (2) tertiary amine oxides wherein at least one of the hydrocarbon groups linked to the nitrogen is a linear or branched alkyl group containing at least 16 carbon atoms. In contrast, the present invention uses quaternary ammonium compounds together with short chain amine oxides (C6-C10) as the thickening system. Also, nowhere in EP-A- 265 979 a source of active oxygen is disclosed.

EP-A-188 025 discloses aqueous stable thickened low-pH bleaching compositions comprising an inorganic peroxy compound, a strong acid and a thickening surfactant. In EP-A-188 025 the thickening surfactant is selected from (1 ) amine oxides wherein at least one of the hydrocarbon groups linked to the nitrogen is a linear or branched alkyl group of C6 to C18 carbon atoms, preferably C12 to C18, (2) amines and (3) quaternary ammonium salts wherein at least one of the hydrocarbon groups linked to the nitrogen is a linear or branched alkyl group of C8 to C18 carbon atoms. Indeed, EP-A-188 025 teaches to use as a thickening surfactant one of these surfactants. And as regards the amine oxides, this patent application teaches to preferably use long chain amine oxides. Also none of the compositions exemplified comprises, as the thickening system, a quaternary ammonium compound together with an amine oxide, let alone a quaternary ammonium compound together with a short chain amine oxide.

Summary of the invention

The present invention encompasses a stable thickened aqueous acidic bleaching composition comprising a source of active oxygen and, as a thickening system, a quaternary ammonium compound and an amine oxide according to the formula R1 R2R3NO wherein R2 and R3 are independently C1-C4 alkyl groups and wherein R1 is a C6 to C10 alkyl group.

In a preferred embodiment the stable thickened aqueous acidic compositions of the present invention further comprise a perfume. The present invention also encompasses a process of treating hard- surfaces wherein a stable thickened aqueous acidic composition, according to the present invention, is used.

The present invention also encompasses a process for the manufacture of a composition according to the present invention wherein :

- an acidic matrix is prepared which comprises at least water, a source of active oxygen and an acid, - then a quaternary ammonium compound is added to said matrix,

- then a perfume, if present, is further added and finally a short chain amine oxide is added,

- the resulting composition is then stirred over at least three hours.

The present invention further encompasses the use of persulfate salt together with a quaternary ammonium compound in an aqueous acidic composition to increase the viscosity of said composition.

Detailed description of the invention

The compositions according to the present invention are stable. By "stable" it is meant herein that a composition comprising a source of active oxygen or mixtures thereof, such as persulfate salt, preferably does not undergo more than 30 % persulfate loss, in six months at room temperature (20°C-25°C). Persulfate concentration can be measured by titration with potassium permanganate after reduction with a solution containing ammonium ferrous sulphate. Said stability test method is well known in the art and is reported, for example, on the technical information sheet of Curox® commercially available from Interox. Alternatively persulfate concentration can also be measured using a chromatography method described in the literature for peracids (F. Di Furia et al., Gas-liquid Chromatography Method for Determination of Peracids, Analyst, Vol 113, May 1988, p 793-795). The compositions according to the present invention comprise, as an essential element, a source of active oxygen or mixtures thereof. The source of active oxygen according to the present invention acts as an oxidizing agent, it increases the ability of the compositions to remove colored stains and organic stains in general, to destroy malodorous molecules and to kill germs. Suitable sources of active oxygen are hydrogen peroxide or sources thereof. As used herein a hydrogen peroxide source refers to any compound which produces hydrogen peroxide when said compound is in contact with water. Suitable water-soluble inorganic sources of hydrogen peroxide for use herein include persulfate, persulfuric acid, percarbonates, metal peroxides, perborates and persilicate salts.

In addition, other classes of peroxides can be used as an alternative to hydrogen peroxide and sources thereof or in combination with hydrogen peroxide and sources thereof. Suitable classes include dialkylperoxides, diacylperoxide, performed percarboxylic acids, organic and inorganic peroxides and/or hydroperoxides. Suitable organic peroxides/hydroperoxides include diacyl and dialkyl peroxides/hydroperoxides such as dibenzoyl peroxide, t-butyl hγdroperoxide, dilauroyl peroxide, dicumyl peroxide, and mixtures thereof. Suitable preformed peroxyacids for use in the compositions according to the present invention include diperoxydodecandioic acid DPDA, magnesium perphthalic acid, perlauric acid, perbenzoic acid, diperoxyazelaic acid and mixtures thereof.

Persulfate salts or mixtures thereof are the preferred sources of active oxygen to be used in the compositions according to the present invention. Preferred persulfate salt to be used herein is the monopersulfate triple salt. One example of monopersulfate salt commercially available is potassium monopersulfate commercialized by Peroxide Chemie GMBH under the trade name Curox®. Other persulfate salts such as dipersulfate salts commercially available from Peroxide Chemie GMBH can be used in the compositions according to the present invention.

The compositions according to the present invention comprise from 0.1 % to 30% by weight of the total composition of said source of active oxygen, or mixtures thereof, preferably from 0.1 % to 20%, and more preferably from 0.1 % to 15%. Persulfate salts are preferred to be used herein, as it has been found that they allow when used together with a quaternary ammonium compound to increase the viscosity of an aqueous acidic composition. This is especially noticeable in said aqueous acidic compositions in absence of perfumes. Indeed, it has now been found that the addition of a persulfate salt such as a monopersulfate salt, as the source of active oxygen, to an aqueous acidic composition comprising a quaternary ammonium compound such as C16 trimethyl ammonium methylsulfate improves the viscosity of said composition as compared to the viscosity of the same composition but without said persulfate salt. It is believed that (HSO₅~) anion coming from persulfate salt like monopersulfate salt strongly interacts with the cation head group of the quaternary ammonium compound displacing its own counterion (e.g., methylsulfate). It is believed that the interaction of persulfate salt like monopersulfate salt with a quaternary ammonium compound plays a significant role in thickening the compositions of the present invention, together with the thickening effect related to the addition of short chain amine oxide to said quaternary ammonium compound.

Thus in another aspect, the present invention further encompasses the use of persulfate salt together with a quaternary ammonium compound in an aqueous acidic composition to increase the viscosity of said composition.

The compositions of the present invention comprise as a further essential element a thickening system. Said thickening system comprises a quaternary ammonium compound, or mixtures thereof, together with a short chain amine oxide, or mixtures thereof.

Suitable quaternary ammonium compounds to be used according to the present invention are quaternary ammonium compounds wherein one or two of the hydrocarbon groups linked to nitrogen are a linear or branched alkyl group of 6 to 30 carbon atoms, preferably of 10 to 25 carbon atoms and more preferably 12 to 20 carbon atoms, saturated or unsaturated, and wherein the other hydrocarbon groups (i.e. three when one hydrocarbon group is a long chain hydrocarbon group as mentioned hereinbefore or two when two hydrocarbon groups are long chain hydrocarbon groups as mentioned hereinbefore) linked to the nitrogen are independently substituted or unsubstituted, linear or branched, alkyl chain of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms and more preferably are methyl groups. In the embodiment of the present invention where persulfate salts or mixtures thereof are used as sources of active oxygen the quaternary ammonium compound is preferably a non-chloride quaternary ammonium compound. The counterion used in said quaternary ammonium compounds are compatible with any source of active oxygen and are selected from the group of fluoride or methyl sulfate, or methylsulfonate, or hydroxide and the like.

Particularly preferred to be used in the compositions of the present invention are trimethγl quaternary ammonium compounds like myristyl trimethyisulfate, cetyl trimethylsulfate and/or tallow tri methylsulfate. Such trimethyl quaternary ammonium compounds are commercially available from Hoechst, or from Albright & Wilson under the trade name EMPIGEN CM®.

The compositions according to the present invention comprise from 0.1 % to 20% by weight of a quaternary ammonium compound, or mixtures thereof, preferably of from 0.1 % to 15%, more preferably of from 0.1 % to 10% and most preferably of from 1 % to 5%.

Suitable short chain amine oxides to be used according to the present invention are amine oxides having the following formula R1R2R3 O wherein RI is a C6 to CIO alkyl group, preferably a C8 to C10 alkyl group and wherein R2 and R3 are independently substituted or unsubstituted, linear or branched alkyl groups of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms and more preferably are methyl groups. R1 may be a linear or branched alkyl group, being saturated or unsaturated. Suitable short chain amine oxides for use herein are preferably compatible with any source of active oxygen. Preferred short chain amine oxides for use herein are for instance natural blend C8/C10 amine oxide available from Hoechst.

The compositions according to the present invention comprise from 0.01 % to 15% by weight of a short chain amine oxide, or mixtures thereof, preferably of from 0.1 % to 10% more preferably of from 0.1 % to 5% and most preferably of from 0.1 % to 3%.

The total level of thickening system, i.e. of quaternary ammonium compound and of short chain amine oxide, to be used in a given aqueous acidic composition comprising a source of active oxygen depends on the thickening desired for said composition, said level being lower than 20%, preferably between 1 % and 15%, more preferably between 1 % and 10% and most preferably between 1 % and 6%.

The compositions of the present invention have a viscosity of more than 250 cps at 20°C, preferably of from 250 cps to 1500 cps and more preferably of from 250 cps to 900 cps, when measured with a Brookfield viscometer at 60 rpm with a spindle n° 2 or with the Carri-med rheometer at 50 dyne/cm2.

Furthermore, the stable thickened aqueous acidic compositions of the present invention comprise a quaternary ammonium compound and a short chain amine oxide, as the thickening system, the weight ratio of said short chain amine oxide to said quaternary ammonium compound being from 1 :2 to 1 :100, preferably from 1 :4 to 1 :30 and more preferably from 1 :10 to 1 :20.

In an embodiment of the present invention the compositions as described hereinbefore further comprise a perfume or mixtures thereof. It is well known that perfumes have a general tendency to significantly decrease the viscosity of compositions in which they are introduced. An advantage of the thickened acidic compositions of the present invention is, that they are less sensitive to the presence of perfume, even the presence of high levels of perfumes. Suitable perfumes to be used herein are all the perfumes well known in the field per se or blend of such perfumes.

The compositions according to the present invention comprise up to 3% by weight of the total composition of a perfume or mixtures thereof, preferably of from 0.1 % to 2% and more preferably of from 0.2% to 1 %. The compositions of the present invention are acidic compositions. In order to obtain appropriate stability of the source of active oxygen in the compositions according to the present invention, said compositions are formulated at a pH between 0 to 6, more preferably at a pH between 0 and 4 and most preferably at a pH between 0 and 2. Acidity further contributes to formulate compositions according to the present invention which exhibit good limescale removing performance while having also good disinfecting properties. Accordingly, the compositions of the present invention further comprise organic and/or inorganic acids. Particularly suitable organic acids to be used herein are aryl and/or alkyl suifonate, such as methane sulfonic acids, citric acid, succinic acid, sulphamic acid and the like. Particularly suitable inorganic acids are sulfuric, phosphoric, nitric acids and the like.

The compositions according to the present invention are aqueous. The compositions according to the present invention comprise from 40% to 99% by weight of the total composition of water, preferably from 60% to 95%, most preferably from 70% to 90%. Deionized water is preferably used.

As an optional but highly preferred ingredient the compositions according to the present invention further comprise an alkali metal sulphate or mixtures thereof. Preferred alkali metal sulphates to be used herein include potassium sulphate, sodium sulphate or mixtures thereof. We have now found that the addition of an alkali metal sulphate in the compositions of the present invention comprising persulfate salt such as monopersulfate salt, as the source of active oxygen, improves the chemical stability of said compositions. Indeed the percentage of monopersulfate lost upon storage time in a liquid composition according to the present invention comprising a given amount of monopersulfate and an alkali metal salt of sulphate is reduced as compared to the percentage of monopersulfate lost upon storage time in the same composition but without said alkali metal sulphate. Monopersulfate concentration can be measured as already defined herein before. It is believed that the addition of an alkali metal sulphate stabilises monopersulfate salts by shifting the following equilibrium to the left hand side: H2O+KHSO4+KHSO5 -, - K2SO +H2SO4+H2O2

Accordingly the compositions according to the present invention comprise up to 10% by weight of the total composition of said alkali metal sulphate or mixtures thereof, preferably from 1 % to 10% and more preferably from 2% to 7%.

In another aspect, the present invention further encompasses the use of an alkali metal sulphate in an aqueous composition comprising a persulfate salt, preferably monopersulfate salt to improve the chemical stability of said composition.

Depending on the end use envisioned, the compositions according to the present invention may further comprise a variety of other ingredients including other surfactants of all types to boost the performance over a wider range of soils/encrustations, organic or inorganic alkalis, dyes, optical brighteners, builders, chelants, pigments, enzymes, dye transfer inhibitors, solvents, buffering agents, stabilizers and the like.

The present invention further encompasses a process of treating hard- surfaces, especially non-horizontal surfaces, wherein a composition according to the present invention is used in its neat or diluted form.

By "in its diluted form" it is meant herein that said compositions may be diluted with water up to 99% of water. Said dilution may occur either before, after or while said composition is applied to a hard-surface.

The compositions herein find a preferred application in the cleaning of toilet bowls and bath tubs. While cleaning toilet bowls compositions according to the present invention may be diluted while or after they are applied to the surface to be cleaned. For example, said compositions may be dispensed from a container onto said hard-surface, then diluted in water and left to act onto said surfaces, then removed by rinsing or flushing.

As used in the foregoing paragraphs, the expression "treating" includes washing as the compositions used in the process according to the present invention comprise surfactants and bleaching agents as said compositions also comprise a source of active oxygen, preferably persulfate salts.

The compositions according to the present invention may be manufactured by adding the different ingredients in any order. However, the desired initial viscosity of an aqueous composition of the present invention is obtained immediately, when following a preferred mixing order for the incorporation of the different ingredients in said composition. Accordingly, the present invention further encompasses a process for the manufacture of the compositions of the present invention, wherein said process comprises the steps of:

- preparing an acidic matrix comprising at least water, a source of active oxygen and an acid,

- adding to said matrix the quaternary ammonium compound, - then adding the perfume if present and finally the short chain amine oxide,

- and as a final step the resulting composition is stirred over at least three hours.

The present invention is further illustrated by the following examples.

Example I

Compositions are made which comprise the listed ingredients in the listed proportions (weight %).

Comoositions #1 #2 #3 #4 #5

C16 trimethyl ammonium 4.0 4.2 5.0 0.0 0.0 methylsulfate

C16/18 trimethyl 0.0 0.0 0.0 4.0 4.0 ammonium methylsulfate

C8/C10 amine oxide 0.2 0.0 0.0 0.2 0.0

Curox® * 6.0 6.0 6.0 6.0 6.0

Methane sulfonic acid 5.0 5.0 5.0 5.0 5.0

Perfume 0.7 0.7 0.7 0.7 0.7

Water and minors up to 100

* Curox® is one of the commercial names of monopersulfate salts * * Viscosity grows with time; therefore, those are the lowest achievable viscosities with the above indicated compositions.

The initial viscosity of the above compositions were measured by a Carri- Med Rheomoter at fixed shear stress (50 dyne/cm²) at 20°C. It has been chosen a standard value of the shear stress to compare the viscosity of the above mentioned compositions, some of which showing a pseudoplastic behaviour. 50 dyne/cm² as shear stress value is representative of a fluid flow occurring on a inclined surface when the product thickness is around 1 mm and the only external force is due to the gravity field as per toilet cleaning application.

Compositions #1 and #4 are representative of the stable thickened aqueous acidic compositions according to the present invention, i.e. they comprise a quaternary ammonium compound and a short chain amine oxide as the thickening system. Compositions #2, #3 and #5 are taken as reference, they are free of short chain amine oxides.

The above data surprisingly show that the addition of a small amount of a short chain amine oxide (0.2% by weight) to a quaternary ammonium compound (4% by weight) in an acidic composition comprising a source of active oxygen, like monopersulfate, allows to formulate a composition having a higher viscosity as compared to the same composition wherein the thickening system used is only a quaternary ammonium compound. (See composition #1 with a viscosity of 300 cps versus composition #2 with a viscosity of 20 cps as well as composition #4 with a viscosity of 960 cps as compared to composition #5 with a viscosity of 30 cps). Also the above data show that the addition of a small amount of short chain amine oxide (0.2% by weight) to quaternary ammonium compound (4% by weight) in an acidic composition comprising a source of active oxygen, like monopersulfate, allows to decrease the level of total thickening surfactant needed to formulate an aqueous acidic composition with a desired viscosity as compared to the use, as a thickening system, of a quaternary ammonium compound alone without any short chain amine oxide (see composition #1 with a level of 4.2% of thickening system according to the present invention versus composition #3 with a level of 5% of thickening system in order to obtain compositions having the same viscosity, i.e. 300 cps). In other words, the present invention allows to formulate thickened aqueous acidic compositions at low total level of thickening surfactants, i.e. to achieve the same viscosity, the thickening system of the present invention used in composition #1 allows a reduction of 16% by weight of the total level of thickening surfactant needed as compared to the level required with composition #3 .

The data also show that the compositions according to the present invention were clear compositions, as opposite to clouded (i.e. not clear) compositions and Newtonian compositions.

Exgmple II

Compositions are made which further illustrate the present invention and which comprise the listed ingredients in the listed proportions (weight %).

Compositions #1 #2 #3 #4 #5

C16 trimethyl ammonium 4.00 4.00 4.00 4.00 4.00 methylsulfate

C8/C10 amine oxide 0.00 0.00 0.30 0.30 0.30

* Curox® is one of the commercial names of monopersulfate salts

* * Viscosity grows with time; therefore, those are the lowest achievable viscosities with the above indicated compositions.

The initial viscosity of the above compositions were measured by a Carri- Med Rheomoter at fixed shear stress (50 dyne/cm²) at 20°C. It has been chosen a standard value of the shear stress to compare the viscosity of the above mentioned compositions, some of which showing a pseudoplastic behaviour. 50 dyne/cm² as shear stress value is representative of a fluid flow occurring on a inclined surface when the product thickness is around 1mm and the only external force is due to the gravity field as per toilet cleaning application.

Compositions #1 and #2 are taken as reference, they are free of short chain amine oxides. Composition #3 is taken as reference, it is free of monopersulfate salt. Compositions #4 and #5 are representative of the stable thickened aqueous acidic compositions according to the present invention, i.e. they comprise a quaternary ammonium compound, a short chain amine oxide and monopersulfate salt.

The above data surprisingly show that the addition of a monopersulfate salt to a acidic aqueous composition comprising a short chain amine oxide and a quaternary ammonium compound allows to formulate a composition having a higher viscosity as compared to the same composition but without said monopersulfate salt. (See compositions #4 and #5 comprising respectively 6% and 4% by weight of the total composition of monopersulfate salt with a viscosity of respectively 300 cps and 250 cps as compared to composition #3 without monopersulfate salt and with a viscosity of 50 cps). Also the above data show the correlation between the increase of the concentration of monopersulfate salt and the increase of viscosity in said matrix.

The above results further show that the present invention allows to formulate thickened aqueous acidic compositions at low total level of thickening surfactants, even if perfume is present, by combining monopersulfate, quaternary ammonium compound and short chain amine oxide .

Example III

Rheological Behaviour Newt. Newt. Newt. Newt.

Example IV

Compositions #1 #2 #3 #4 #5 #6

C16 trimethyl ammonium 4.00 4.00 4.00 4.00 4.00 4.00 methylsulfate

C8/C10 amine oxide 0.30 0.10 0.30 0.30 0.30 0.30

Curox® * 6.00 6.00 6.00 6.00 6.00 6.00

Methanesulfonic acid 10.00 15.00 0.00 0.00 5.00 0.00

Sulfuric acid 0.00 0.00 3.00 6.00 6.00 0.00

Phosphoric acid 0.00 0.00 0.00 0.00 0.00 12.00

Perfume 0.70 0.70 0.70 0.70 0.70 0.70

Water and minors up to 100

PH 0.66 0.35 1.00 0.78 0.50 1.00

Initial viscosity (cps) 270 330 380 400 300 320

Appearance clear clear clear clear clear clear

Rheological Behaviour Newt. Newt. Newt. Newt. Newt. Newt.

Curox® is one of the commercial names of monopersulfate salts.

All the above mentioned acidic aqueous compositions comprising monopersulfate provide significant benefits in toilet soils cleaning both when used neat or diluted. Said compositions were found to be stable over long periods of time. Indeed, these compositions had not more than 10% loss after 1 month at room temperature.

Claims

WHAT IS CLAIMED IS :

1. A stable thickened aqueous acidic composition comprising a source of active oxygen, a quaternary ammonium compound and an amine oxide having the following formula R1 R2R3NO wherein R2 and R3 are independently C1-C4 alkyl groups and wherein R-* is a C6 to C10 alkyl group.

2. A composition according to claim 1 wherein said quaternary ammonium compound is a quaternary ammonium compound wherein one or two of the hydrocarbon groups linked to nitrogen are a linear or branched alkyl group of 6 to 30 carbon atoms, preferably of 10 to 25 carbon atoms and more preferably of 12 to 20 carbon atoms, saturated or unsaturated, and wherein the other hydrocarbon groups linked to the nitrogen are independently substituted or unsubstituted, linear or branched alkyl chain of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms and more preferably are methyl groups and wherein the counterion used in said quaternary ammonium compound is preferably selected from the group of fluoride, or methyl sulfate, or methylsulfonate or hydroxide.

3. A composition according to any of the preceding claims wherein in said amine oxide having the formula R1 R2R3NO, R1 is a C8 to C10 alkyl group, and R2 and R3 are independently alkyl groups of from 1 to 3 carbon atoms, and preferably are methyl groups.

4. A composition according to any of the preceding claims wherein said composition comprises from 0.01 % to 15% by weight of the total composition of said amine oxide, or mixtures thereof, preferably of from 0.1 % to 10% and more preferably of from 0.1 % to 5%.

5. A composition according to any of the preceding claims wherein said composition comprises from 0.1 % to 20% by weight of the total composition of said quaternary ammonium compound, or mixtures thereof, preferably of from 0.1 % to 15% and more preferably of from 0.1 to 10%.

6. A composition according to any of the preceding claims wherein in said composition the weight ratio of said amine oxide to said quaternary ammonium compounds is from 1 :2 to 1 :100, preferably from 1 :4 to 1 :30 and more preferably from 1 :10 to 1 :20.

7. A composition according to any of the preceding claims wherein the total level of said quaternary ammonium compound and said amine oxide is no more than 20%, preferably between 1 % to 15%, more preferably between 1 % to 10% and most preferably between 1 % to 6%.

8. A composition according to any of the preceding claims wherein said composition has a viscosity of more than 250 cps, preferably of from

250 cps to 1500 cps and more preferably of from 250 cps to 900 cps.

9. A composition according to any of the preceding claims wherein the pH of said composition Is from 0 to 6, preferably from 0 to 4 and more preferably from 0 to 2.

10. A composition according to any of the preceding claims wherein said composition further comprises a perfume, preferably at a level of from 0% to 3% by weight of the total composition, more preferably at a level of from 0.1 % to 2% and most preferably at a level of from 0.2% to 1 %.

1 1. A composition according to any of the preceding claims wherein said source of active oxygen is a persulfate salt, preferably monopersulfate, and is present at a level of from 0.1 % to 30% by weight of the total composition, preferably at a level of from 0.1 % to 20% and more preferably at a level of from 0.1 % to 15%.

12. A composition according to any of the preceding claims wherein said composition further comprises an alkali metal sulphate, preferably potassium sulphate, sodium sulphate or mixtures thereof, in an amount up to 10% by weight of the total composition, preferably from 1 % to 10% and more preferably from 2% to 7%.

13. A process of treating hard-surfaces wherein a composition according to any of the preceding claims is used.

14. A process for the manufacture of a composition according to any of claims 1 to 12 wherein in said process :

- an acidic matrix is prepared which comprises at least said water, said source of active oxygen and said acid,

■ - then said quaternary ammonium compound is added to said matrix,

- then said perfume, if present, is further added and finally said amine oxide is added,

- the resulting composition is then stirred over at least three hours.

15. The use of an alkali metal sulphate in an aqueous composition comprising a persulfate salt, preferably monopersulfate salt, to improve the chemical stability of said composition.

16. The use of a persulfate salt together with a quaternary ammonium compound in an aqueous acidic composition to increase the viscosity of said composition.